op hamilton



Patented Feb. 26,1929.

mil-TED STATES PATENT OFFICE.

' :rosnrn G...-DONALDSON AND HENRY L. conns, or HAMILTON, iomo, ASSIGNORS 'To GUARDIAN METALS COMPANY, or HAMILTON, OHIO, A CORPbRAT-IQN or DELAWARE.

COMPOSITE ARTICLE AND PROCESS OF FORMING THE SAME.

Ne thawing:

This invention relates to steel and other 'metals suitable for use in the safe and vault industry, particularly metals which will'resist penetration by the drill or by the local application of heat (as by the blow torch) and preferably alloyed or united thereto. In

ourpresent invention we describe an improved material WlllCll may be utllized 1n the same way, 1. e., as a core encompassed in metal.

We do not, however, limit ourselvestotheuse of this material as a core as the-same has many commercial uses outside of its use as a 10 core material.

We have found that highly refractory materials can be formed by taking a high-melting pointoxide-such as the oxide of 'zirconiumand binding this together with a suit- 2 able binder such as a high melting point silicate. Zirconium silicate has been found. to

' give excellent results for this purpose. Preferably' these materials should be finely comminuted and thoroughly mixed. They 80 should then be placed in an electric furnace and heated for a sufficient length of time to permit the whole mass to becomes thoroughly fused.

, Instead of adding the zirconium silicate 85 as such, we have obtained excellent results by adding to the zirconium oxide approximately 9 to 11% silicon dioxide. When these substances have been comminuted and th'oroughly mixed, the silicon dioxide and zir- 40 conium dioxide form zirconium silicate .which, being in contact with an excess of zirconium dioxide, forms mixed crystals with the same and acts as a binder for the .entire mass. To either of the above substances we have found it highly advantageous to add from 7 to 10 percent of carbon in a suitable Application filed November 17, 1922. Serial No. 601,616.

form, such as graphite. A typical formula covering such a mixture is as'follows:

Graphite 7% to il Silicon dioxide (SiO 9 to 11 Zirconium dioxide (ZrO 80 fi to 82 It is our present belief that the silicon dioxide should not exceed 12% of the entire formula.

Ores containing zirconium or zirconium silicate not infrequently carry impurities of iron and titanium oxide. We have found that these materials-are detrimental to the formulaand that the best results are obtained when either of these impurities constitutes less than 1% of the formula. The addition of carbon to the formula adds very greatly to the resistance of the finished material. This is doubtless brought about by the fact that the carbon forms metallic carbides which are present as crystals or in solid solution.

When the material herein described is used as a core, it is given asuitable size and shape and combined with a suitable metal, such as steel, as by being encased wholly or partially therein. The core is preferably placed in a mould, metal (such as steel) being poured around it, as described-in our former application above referred to. Thereupon the core material and encompassing material are brought into permanent uniona's possible by the a loying action which takes place at and adjacent to the areas in contact to form what may be. termed metal stock. In any event there is a permanent union between the core and the surrounding metal. This union may also be considered as being accomplished by the surrounding metal penetrating the core more than a weld depth and chemically combining with at least one of the elements comprising the core. This last explanation, it is believed, is satisfactory when the amount of graphite introduced is in excess of the amount that will be dissolved in the silicate thereby permitting the surrounding metal to combine with the excess graphite in the core.

In addition, it has been found that an excess of graphite creates a somewhat porous condition of the core thereby permitting the metal to penetrate the same-and to combine with the graphite to assist in forming the permanent union. The metal stock so formed is more highly resistant to penetration either by the drill or by the torch thanany other parts of the material not subjected to such alloying action. In the matter of attempt to penetrate by means of the localized application of high heat, an important factor is the capacity of the material to conduct the heat away from the point of attack, thereby, in effect, diminishing the available cutting or fusing power of the torch. Refractory materials, o the type described, are excellent nonconductors of heat when cold but become conductors. of heat when raised to a high temperature and thus serve to dissipate the heat.

Cores containing a large proportion of zirconia have been found to shrink considerably when the same are cooled. To overcome this objection, we frequently break up the core after the first melting and re-melt same. The core formed by this second fusion *will be found to be practically free from shrinkage cracks and to be more coherent than those cores which have been fused only once. These cores can be put in strata which may be continuous throughout the metal or they maybe placed in blocks which are set in staggered courses or the material may be broken into any desired size or the core may be formed by binding together with a suitable binder the broken pieces, all set forth in our previous application. In any event, the cores, made as herein described, are intensely hard and impenetrable by the drill. They are also substantially immune from attack by the blow torch. Furthermore, the core material, be ing a non-conductor of electricity, it is impossible to penetrate the same by means of the local application of the electric arc.

Having now described our invention, what we claim and desire to secure by LettersPatent is:

1. A metal stock composed of a core of refractory material which is highly resistant to drill and local high heat, and a metal of higher heat conductivity than the core, said metal surrounding a substantial part of said core and impregnating the same more than a weld depth and chemically combining with at least one element of said core, said stock by reason of the higher heat conductivity of said surrounding metal having the ability to conduct heat from said core thereby preventingt puncture of said stock by local high we 2. A metal stock composed of a coreof refractory material which is highly resistant to drill and local hi h heat, and a metal which surrounds a su stantial part of said core and penetrates the same more than a weld depth and chemically combines with one of the elements thereof, said metal being of higher heat conductivity than said core, said core adapted to conduct heat at a greater rate when warm than when cold, but being of less heat conductivity when warm than the surrounding metal, said stock by reason of the higher heat conductivity of said surrounding metal having the ability to conduct heat from said core thereby preventing puncture of said stock by local high heat.

3. A metal stock composed of a core of refractory material which is-highly resistant to drill and local hi 11 heat, and a metal which surrounds a sulistantial part of said core and penetrates the same more than a Weld depth and chemically combines with one of the elements thereof, said metal being'of higher heat conductivity than said core, said core being composed of upwards of of a high meltin point oxide, less than 30% of a high melting point silicate, and graphite.

4. A metal stock composed of a core of refractory material which is highly resistant to drill' and'local hi h heat, and a metal which surrounds a sulwtantial part of said core and penetrates the same more than a weld depth and chemically combines with one of the elements thereof, said metal being of. higher heat conductivit than said core, said core being composed o zirconium oxide, zirconium silicate, and graphite.

5. A metal stock composed of a core of refractory material which is highly resistant to drill and local high heat, and a metal.

which surrounds a substantial part of said core and penetrates the same more than a weld depth and chemically combines with one of the elements thereof, said metal being of higher heat conductivity than said core, said core being composed of zirconium oxide, zirconium silicate, and gra bite in excess of the amount required to e dissolved in said silicate.

.. 6-. A metal stock composed of a core of re fractory material which is hi hly resistant to drill and local high heat, an a metal which surrounds a substantial part of said core and penetrates the same more than a weld depth and chemically combines with one of the eleterial and said metal.

by a union is formed-between said fused ma- 8. The process of producing a metallic article which consists in mixing zirconium oxide and zirconium silicate, adding graphite thereto in quantity greater than is absorbed 5 by said silicate, heating the mixture to fusion,

cooling, preheating the fused material to approximately 1000 (3., and pouring molten metal around said preheated material Where- 5 by a union is formed between said fused ma- 1 terial and said metal.

9. The process of producing a metallic article which consists in mixing zirconium oxide and zirconium silicate, heating the mixture to fusion, adding graphite to said mixture when the fusion has been nearly accomplished', cooling, preheating said fused material, and pouring molten metal around said preheated fused material.

This specification signed this 13th day of November, 1922. V

JOSEPH G. DONALDSON.

HENRY L. COLES. 

